RESEARCH ARTICLE

Change in Predicted 10-Year Cardiovascular Risk FollowingLaparoscopic Roux-en-Y Gastric Bypass Surgery

David Arterburn & Daniel P. Schauer & Ruth E. Wise &Keith S. Gersin & David R. Fischer &Calvin A. Selwyn Jr & Anne Erisman & Joel Tsevat

Received: 31 March 2008 /Accepted: 7 April 2008 /Published online: 13 August 2008# Springer Science + Business Media, LLC 2008

AbstractBackground Bariatric surgery is being conducted moreoften for morbid obesity, but little evidence exists abouthow it affects the risk of future cardiovascular events. Thegoal of this study was to quantify the change in predicted10-year cardiovascular risk following laparoscopic Roux-en-Y gastric bypass (LRYGBP).Methods We conducted a prospective clinical study ofmorbidly obese adults undergoing LRYGBP at a university

hospital in the USA. Our primary outcome measure wasmean change in 10-year cardiovascular risk at 12 months.We estimated cardiovascular risk by using the Framinghamrisk equation, which calculates the absolute risk ofcardiovascular events for patients with no known historyof heart disease, stroke, or peripheral vascular disease byusing information on age, sex, blood pressure, total andhigh-density lipoprotein cholesterol levels, smoking status,and history of diabetes.Results Ninety-two participants underwent LRYGBP be-tween December 2004 and October 2005. Their predictedbaseline 10-year cardiovascular risk was 6.7%. At 6 and12 months, their predicted risk had decreased to 5.2% and5.4%, respectively. Assuming no change in risk amonguntreated patients, this represents an absolute risk reductionof 1.3%; which suggests that 77 morbidly obese patientswould have to undergo LRYGBP to avert one new case ofcardiovascular disease over the ensuing 10 years (numberneeded to treat=77).Conclusion Our findings indicate that LRYGBP is associ-ated with improvements in cardiovascular risk factors and acorresponding decrease in predicted 10-year risk of cardio-vascular disease.

Keywords Morbid obesity . Cardiovascular diseases .

Risk factors . Diabetes mellitus . Hypertension .

Hyperlipidemia . Gastric bypass

Introduction

The prevalence of morbid obesity [defined as a body massindex (BMI) 40 kg/m2] has increased rapidly in the USA,from 0.8% in 19601962 to 4.8% in 20032004 [1, 2].

OBES SURG (2009) 19:184189DOI 10.1007/s11695-008-9534-7

D. Arterburn (*)Group Health Center for Health Studies,1730 Minor Ave, Suite 1600,Seattle, WA 98101, USAe-mail: arterburn.d@ghc.org

D. ArterburnDepartment of Medicine, University of Washington,Seattle, WA, USA

D. P. Schauer :R. E. Wise : J. TsevatDepartment of Medicine, University of Cincinnati,Cincinnati, OH, USA

K. S. GersinGeneral Surgery, Carolinas Medical Center,Charlotte, NC, USA

D. R. Fischer :A. ErismanDepartment of Surgery, University of Cincinnati,Cincinnati, OH, USA

C. A. Selwyn JrGeneral Surgery, Ministry Medical Group,Stevens Point, WI, USA

J. TsevatCincinnati Veterans Affairs Medical Center,Cincinnati, OH, USA

Morbid obesity is associated with a substantially greaterrisk of morbidity and mortality from chronic healthconditions, such as diabetes, hypertension, cardiovasculardisease, and cancer [3, 4]; it has been linked to multidi-mensional impairments in health-related quality of life andpsychosocial well-being [5]. The economic burden ofmorbid obesity among US adults is also substantial:Healthcare expenditures for morbidly obese adults are81% greater than for normal-weight adults [6]. In 2000,aggregate US healthcare expenditures associated withexcess body weight among morbidly obese adults exceeded$11 billion [6].

The health and economic impacts of morbid obesityunderscore the urgent need to identify effective treatments.Unfortunately, dietary, behavioral, and drug treatmentoptions frequently fail to result in sustained, clinicallymeaningful weight loss in patients with morbid obesity [7].On the other hand, a growing body of evidence demon-strates that bariatric surgery can promote sustained weightloss and improvements in diabetes and other cardiovascularrisk factors [8, 9]. Less evidence suggests that bariatricsurgery can reduce the risk of future cardiovascular events[1012].

An individuals probability of developing cardiovasculardisease over the next 10 years can be estimated bycalculating a Framingham risk score, which uses informa-tion on age, sex, blood pressure, current smoking status,presence or absence of diabetes, and levels of total andhigh-density lipoprotein (HDL) cholesterol to summarizethe combined 10-year risk of angina pectoris, myocardialinfarction, unstable angina, and cardiovascular death [13].The Framingham risk equations were developed in a largeprospective cohort of US men and women age 3074 years;the equations have been validated in multiple diversepopulations and discriminate well among those who willhave a cardiovascular event and those who will not [14].The goal of this study was to quantify the change inpredicted 10-year cardiovascular risk following laparoscop-ic Roux-en-Y gastric bypass (LRYGBP) among adults withmorbid obesity.

Materials and Methods

We conducted a prospective clinical study of 100 morbidlyobese adults undergoing LRYGBP at the University ofCincinnatis Center for Surgical Weight Loss betweenDecember 2004 and November 2006. Data analyses werecompleted at Group Health in Seattle, WA, USA. Theinstitutional review boards of the University of Cincinnatiand Group Health reviewed and approved all studyprocedures.

Study Population

Based on 1998 National Institutes of Health guidelines,patients eligible for LRYGBP had either a BMI40 kg/m2,or a BMI35 kg/m2 and one or more obesity-associatedchronic medical condition(s) that had not improved withprevious behavioral and/or drug treatments for weight loss.All the patients received comprehensive preoperativedietary and behavioral counseling. The patients alsounderwent a preoperative evaluation by an internist andpsychologist. The patients who completed those evaluationsand demonstrated a clear understanding of the extensivedietary, exercise, and medical implications of weight losssurgery were considered eligible for the procedure.

Data Collection Procedures

In accordance with Health Insurance Portability andAccountability Act regulations, we asked consecutivemorbidly obese patients scheduled for LRYGBP to partic-ipate in this study and obtained written informed consentfrom all participants. Study participants had the followingclinical and laboratory assessments performed at baseline(preoperative), 6 months, and 12 months after surgery:body weight, blood pressure, and levels of hemoglobin A1c(HbA1c), fasting blood sugar, and fasting serum cholesterol[triglycerides and total, HDL, and low-density lipoprotein(LDL) cholesterol]. A trained research nurse specialistextracted these clinical and laboratory data from paperand electronic medical record databases and extractedinformation on length of hospital stay and operative andpostoperative complications.

The primary outcome measure in this study was meanchange in 10-year cardiovascular risk. This risk wasestimated at baseline, 6 months, and 12 months using theFramingham risk equation [13]. This equation calculatesthe absolute risk of coronary heart disease (CHD) events forpatients with no known history of CHD, stroke, orperipheral vascular disease, based on patients age, sex,blood pressure, total and HDL cholesterol levels, smokingstatus, and history of diabetes [13, 14]. Secondary out-comes included body weight, BMI, systolic and diastolicblood pressure, fasting serum cholesterol levels, fastingglucose level, and HbA1c level.

Statistical Analyses

We examined mean 12-month changes in our secondaryoutcomes using the paired t test. The effect of LRYGBP on10-year cardiovascular risk was examined as the meandifference in percentage risk over 12 months by using thepaired t test. Based on the published literature regarding

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changes in cardiovascular risk factors following bariatricsurgery, we expected to observe a mean reduction in 10-year cardiovascular risk from 7 to 3% over 1-year follow-up [1519]. We estimated that a sample of 100 patientswould result in more than 99% power to detect a 4%change in 10-year cardiovascular over 1-year follow-up(given an alpha of 0.05). P values

modest, but statistically significant, reduction in systolicblood pressure over the 12-month follow-up; however,diastolic blood pressure readings did not change signifi-cantly. Among 24 patients with uncontrolled hypertensionat baseline, the mean decrease in systolic blood pressure at12 months was 153 mmHg (p=0.0002).

Fasting blood glucose and HbA1c levels decreasedsignificantly by 6 and 12 months following LRYGBP(Table 2). Among patients with diabetes at baseline, themean changes in fasting glucose and HbA1c at 12 monthswere 379 mg/dl (p=0.0001) and 1.10.3% (p=0.0004), respectively. Triglyceride and total and LDLcholesterol levels were all significantly reduced at 6 and

12 months (Table 2). HDL cholesterol levels decreased at6 months but increased at 12 months.

The average 10-year cardiovascular risk decreased from6.7% at baseline to 5.2% at 6 months and 5.4% at12 months follow-up. Assuming no change in cardiovas-cular risk among morbidly obese patients who do notundergo bariatric surgery, this represents an estimatedabsolute risk reduction of 1.3%; thus, 77 morbidly obesepatients would have to undergo LRYGBP to avert one newcase of cardiovascular disease over the ensuing 10 years(NNT=77). Although baseline levels of risk differedbetween men and women, reductions in cardiovascular riskoccurred to a similar degree in both (Fig. 1). Patients withdiabetes and those older than 45 years had larger decreasesin 10-year cardiovascular risk, compared to adults withoutdiabetes and those younger than 45 years (Fig. 1).

Discussion

Several investigators have independently reported improve-ments in blood pressure [15, 16], serum cholesterol level[17, 18], fasting blood sugar level [19, 22], or HbA1c level[19] following bariatric surgery. However, few studies havesimultaneously examined changes in all of those riskfactors. In the present study, we found that LRYGBP isassociated with statistically significant improvements in allcardiovascular risk factors and a corresponding decrease inpredicted 10-year risk of cardiovascular disease. Our resultssuggest that one would need to treat 77 morbidly obesepatients with LRYGBP to prevent one incident case ofcardiovascular disease over the ensuing 10 years.

Our findings are consistent with those of three recentstudies of changes in cardiovascular risk following RYGBP

Table 2 Baseline, 6-month, and 12-month clinical and laboratory measures of 92 Roux-en-Y gastric bypass cases

Characteristic Baseline(n=92)

6-monthcompleters(n=63)

6-monthBOCF(n=92)

p valuea 12-monthcompleters(n=42)

12-monthBOCF(n=92)

p valueb

Weight (kg), meanSD 14229 10423 11229

[1012]. Vogel and colleagues reported a retrospectiveanalysis of 109 consecutive RYGBP cases at one hospital inMichigan. Their findings for changes in body weight,HbA1c, glucose, triglycerides, and HDL, LDL, and totalcholesterol were similar to ours in magnitude and direction.Vogel et al. reported 10-year Framingham cardiovascularrisk estimates at baseline and 17 months after surgery of65% and 43% (p

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9. Sjostrom L, Lindroos AK, Peltonen M, et al. Lifestyle, diabetes,and cardiovascular risk factors 10 years after bariatric surgery. NEngl J Med. 2004 Dec 23;351(26):268393.

10. Vogel JA, Franklin BA, Zalesin KC, et al. Reduction in predictedcoronary heart disease risk after substantial weight reduction afterbariatric surgery. Am J Cardiol. 2007 Jan 15;99(2):2226.

11. Batsis JA, Romero-Corral A, Collazo-Clavell ML, et al. Effect ofweight loss on predicted cardiovascular risk: change in cardiacrisk after bariatric surgery. Obesity (Silver Spring). 2007 Mar;15(3):77284.

12. Torquati A, Wright K, Melvin W, Richards W. Effect of gastricbypass operation on Framingham and actual risk of cardiovas-cular events in class II to III obesity. J Am Coll Surg. 2007 May;204(5):77682; discussion 78273.

13. Grundy SM, Pasternak R, Greenland P, Smith S Jr, Fuster V.Assessment of cardiovascular risk by use of multiple-risk-factorassessment equations: a statement for healthcare professionalsfrom the American Heart Association and the American Collegeof Cardiology. Circulation. 1999 Sep 28;100(13):148192.

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15. Foley EF, Benotti PN, Borlase BC, Hollingshead J, BlackburnGL. Impact of gastric restrictive surgery on hypertension in themorbidly obese. Am J Surg. 1992 Mar;163(3):2947.

16. Carson JL, Ruddy ME, Duff AE, Holmes NJ, Cody RP, BrolinRE. The effect of gastric bypass surgery on hypertension inmorbidly obese patients. Arch Intern Med. 1994 Jan 24;154(2):193200.

17. Jones KB Jr. The effect of gastric bypass on cholesterol, HDL, andthe risk of coronary heart disease. Obes Surg. Feb 1992;2(1):835.

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22. Leonetti F, Silecchia G, Iacobellis G, et al. Different plasmaghrelin levels after laparoscopic gastric bypass and adjustablegastric banding in morbid obese subjects. J Clin EndocrinolMetab. 2003 Sep;88(9):422731.

23. Snow LL,Weinstein LS, Hannon JK, et al. The effect of Roux-en-Ygastric bypass on prescription drug costs. Obes Surg. 2004 Sep;14(8):10315.

24. Narbro K, Agren G, Jonsson E, Naslund I, Sjostrom L, PeltonenM. Pharmaceutical costs in obese individuals: comparison with arandomly selected population sample and long-term changes afterconventional and surgical treatment: the SOS intervention study.Arch Intern Med. 2002 Oct 14;162(18):20619.

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Change in Predicted 10-Year Cardiovascular Risk Following Laparoscopic Roux-en-Y Gastric Bypass SurgeryAbstractAbstractAbstractAbstractAbstractIntroductionMaterials and MethodsStudy PopulationData Collection ProceduresStatistical Analyses

ResultsDiscussionReferences

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